1. Field of the Invention
The invention relates to a method and an apparatus for tunneling service of explicit multicast in a mobile IP network, and more specifically to a method and an apparatus for tunneling service of explicit multicast in a mobile IP network for transmitting a multicast packet to plural mobile nodes efficiently.
2. Description of the Related Art
Generally, mobile IP, such as used in cellular telephone networks, is used for receiving a data packet having an address within a home network continuously while the Internet node which connects with a network (home network) on regular basis connects with another network (foreign network) temporarily. In turn, the Internet node connecting with the foreign network is called a mobile node.
Plural mobile nodes are provided with Internet multicast service on the mobile IP network in two ways. According to the first method, the mobile node is provided with the multicast service by joining with a multicast group through the multicast router on a foreign network in which the mobile node visits. According to the second method the mobile node is provided with the multicast service by joining with a multicast group through a home agent.
Upon comparison, the first method has an advantage that the mobile node can receive the multicast packet via relatively optimized path when the mobile node receives the multicast packet from the outside of the network, but this requires that the foreign network that the mobile node visits uses a router to provide the multicast service. However, the first method is not available if the mobile node is set up unless the multicast service should be provided for security reasons when the mobile node connects with a foreign network.
As described above, the multicast service is typically provided in the mobile IP network by a home agent to prevent the problems of multicast service occurring through the path on the foreign network.